Angular adjustment mechanism

ABSTRACT

An angular adjustment mechanism (11) for precisely adjusting an eyepiece (12) of an optical assembly (10) through the use of a system of levers. The system of levers acts to allow the eyepiece (12) and a mirror (24), disposed within the assembly (10), to rotate about a common axis (28), with the eyepiece (12) rotating at two times the angular speed of the mirror (24). The relative angular movement of the eyepiece (12) and the mirror (24) allows a user to obtain a comfortable viewing position without disturbing the alignment of the optical assembly (10). Furthermore, the relative angular movement of the eyepiece (12) and the mirror (24) does not significantly effect the imaging of the optical assembly (10), or cause optical image shifts.

BACKGROUND OF THE INVENTION

The present invention generally relates to the adjustment of optical assemblies and, in particular, relates to one such mechanism for rotating two optical assemblies about a common axis, one at two times the angular speed of the other, through the use of a system of levers.

The use of microscopes, telescopes, and other optical assemblies is presently widespread and is expanding due to advances in optical technology. The users of such optical assemblies typically must spend a considerable amount of time peering through an eyepiece that is attached to the optical assembly. The position of the eyepiece with respect to the position of a particular user varies depending upon the type of optical assembly being used, the location where the optical assembly is situated, and the size of the particular user. To provide a user with a comfortable viewing position, many optical assemblies are comprised of some sort of means for adjusting the position of the eyepiece with respect to the position of the user.

To date, the position of an eyepiece of an optical assembly has typically been adjusted through the use of a series of gears. Such gears are rotatably mounted to the optical assembly so as to allow the eyepiece to move in a precise manner with respect to the rest of the optical assembly. These gears must be accurately machined and fitted so as to allow such precise eyepiece movement without significantly affecting the imaging of the optical assembly, or causing optical image shifts. The machining and fitting processes are painstakingly tedious and, even when considerable care is given to these processes, backlash problems can still occur if the gears become loosely engaged due to any depreciative effects on the gear teeth over time or due to debris becoming caught between the gear teeth.

To overcome the above-mentioned shortcomings associated with using a series of gears to adjust the position of an eyepiece of an optical assembly, emphasis must be placed on manufacturing a suitable replacement at low cost. Otherwise, a high cost solution to overcome the above-mentioned shortcomings would reap no benefits in a competitive marketplace. It would therefore be desirable to overcome the shortcomings of the above-mentioned prior art adjustment means, while providing a simple, low cost mechanism for precisely adjusting the eyepiece of an optical assembly without causing significant optical image shifts.

SUMMARY OF THE INVENTION

The present invention contemplates a simple, low cost mechanism for precisely adjusting an eyepiece of an optical assembly through the use of a system of levers. The system of levers acts to allow the eyepiece and a mirror, disposed within the assembly, to rotate about a common axis, with the eyepiece rotating at two times the angular speed of the mirror. The relative angular movement of the eyepiece and the mirror allows a user to obtain a comfortable viewing position without disturbing the alignment of the optical assembly. Furthermore, the relative angular movement of the eyepiece and the mirror does not significantly effect the imaging of the optical assembly, or cause optical image shifts.

From the above descriptive summary, it is apparent how the present invention angular adjustment mechanism overcomes the shortcomings of the above-mentioned prior art.

Accordingly, it is one objective of the present invention is to provide a simple, low cost mechanism for precisely adjusting an eyepiece of an optical assembly using a system of levers whereby there are no significant effects on the imaging of the optical assembly, or optical image shifts. This object is accomplished, at least in part, by a mechanism employing a system of levers.

Other objectives and advantages of the present invention will become apparent to those skilled in the an from the following derailed description read in conjunction with the appended claims and the drawings appended hereto.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to facilitate a fuller understanding of the present invention, reference is now made to the appended drawings. These drawings, not drawn to scale, should not be construed as limiting the present invention, but are intended to be exemplary only.

FIG. 1 is a partial cross-sectional side view of a binocular of an ophthalmoscope that is adjustable by way of an angular adjustment mechanism according to the present invention;

FIG. 2 is an isolated side view of the binocular prism frame shown in FIG. 1 with a first lever integrated therein;

FIG. 3 is an isolated side view of the present invention angular adjustment mechanism shown in FIG. 1;

FIG. 4 is a partial cross-sectional isolated end view of the present invention angular adjustment mechanism shown in FIG. 1, taken along lines 4a-4c and 4b-4c of FIG. 3; and

FIG. 5 is a partial cross-sectional isolated side view of the present invention angular adjustment mechanism shown in FIG. 1, wherein the mechanism is shown in its two extreme angular positions.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1, there is shown an assembly 10 of a binocular of an ophthalmoscope that is adjustable by way of an angular adjustment mechanism 11 according to the present invention. The assembly 10 is first comprised of an eyepiece 12 through which a user 14 peers through. The eyepiece 12 is attached to a first prism frame 32 that contains a first prism 18, with reflecting surfaces 20, a second prism 21, and a third prism 22 for creating an optical path between the eyepiece 12, or the user 14, and a mirror 24. The mirror 24 is mounted to a mirror mount 26 that in turn is rotatably attached to a shaft 45 such that the mirror mount 26 is rotated about a first axis 28. Thus, the mirror mount 26 and the mirror 24 are both rotatable about the first axis 28 at a first common angular speed.

The first prism 18 is secured to a first prism frame 32, a portion of which is rotatable along axis 34 to allow the eyepiece 12 to be adjusted without disturbing the optical path between the eyepiece 12, or the user 14, and the mirror 24. The first prism 18 is secured to the first prism frame 32 with an adhesive that is applied to two sides (only one side shown) of the first prism at point 30. The first prism frame 32 is secured to the second prism frame 42 with a shaft screw at axis 34. The second prism 21 is secured to the third prism 22 with an adhesive that is applied at their interface 23. The third prism 22 is secured to a second prism frame 42 that is rotatable about the first axis 28. The third prism 22 is secured to the second prism frame 42 with an adhesive that is applied to two sides of the third prism 22 at points 38 and 40. The adhesive for securing the third prism 22 is applied through two corresponding ports 39 and 41 formed within the second prism frame 42. The second prism frame 42 is secured to the shaft 45 at axis 28. The housing 16 is attached to the frame 42, for example, with a pair of screws at locations 36 and 44 as shown in FIG. 2. Thus, the first prism frame 32, the first prism 18, the second prism frame 42, the second prism 21, the third prism 22, the housing 16, and the eyepiece 12 are all rotatable about the first axis 28 at a second common angular speed. It should be noted that the first axis 28 is maintained by the shaft 45 that protrudes from a support 46 which is secured to a main frame of an ophthalmoscope (not shown) with a pair of bolts (not shown) at points 48 and 50.

The assembly 10 as described so far is a typical ophthalmoscope binocular assembly. This typical ophthalmoscope binocular assembly is enhanced with the addition of the angular adjustment mechanism 11, as will now be described.

Referring to FIG. 2, the second prism frame 42 is shown having an aperture 52 for accepting shaft 45 so as to permit its rotation about the first axis 28. The second prism frame 42 also has a first lever 54 integrated therein. This first lever 54 is equipped with a circular pivot region 56, the center of which is at a radial distance, R₁, from the center of the aperture 52.

Referring back to FIG. 1, a second lever 58 is shown having a circular pivot region 60 on one end for accepting a pin 62 protruding from the support 46, and a circular pivot region 64 on the other end for accepting a pin 66 protruding from a third lever 68 having an "L" shape. Since the support 46, and thus the pin 62, are stationary, the second lever 58 is rotatable about a second axis 70. On the other hand, the third lever 68, and thus the pin 66, are not stationary. Thus, the second lever 58 and the third lever 68 are relatively rotatable about a third axis 72. The circular pivot region 56 of the first lever 54 accepts a pin 74 also protruding from the third lever 68. Similar to the second lever 58, the first lever 54 and the third lever 68 are relatively rotatable about a fourth axis 76. It should be noted that the distance between the center of aperture 52 and the center of circular pivot region 60, or the center of shaft 45 and the center of pin 62, or the first axis 28 and the second axis 70, is equal to R₂. It should also be noted that the distance between the center of circular pivot region 60 and the center of circular pivot region 64, or the center of pin 62 and the center of pin 66, or the second axis 70 and the third axis 72, is equal to R₁. It should further be noted that the distance between the center of circular pivot region 64 and the center of circular pivot region 56, or the center of pin 66 and the center of pin 74, or the third axis 72 and the fourth axis 76, is equal to R₂. The circular pivots mentioned herein include an aperture for receiving the pins.

Integrated into the mirror mount 26 is a fourth lever 78 which, like the mirror mount itself, is rotatable about the first axis 28. Protruding from the fourth lever 78 is a pin 80. A fifth lever 82 is shown having circular pivot region 84 on one end for accepting the pin 80, and a circular pivot region 86 on the other end for accepting a pin 88 protruding from the third lever 68. Neither the fourth lever 78, and thus the pin 80, or the fifth lever 82 are stationary. Thus, the fourth lever 78 and the fifth lever 82 are relatively rotatable about a fifth axis 90. Similarly, the third lever 68 and the fifth lever 82 are relatively rotatable about a sixth axis 92. It should be noted that the distance between the center of aperture 52 and the center of circular pivot region 84, or the center of shaft 45 and the center of pin 80, or the first axis 28 and the fifth axis 90, is equal to 2R₁, or R₃. It should also be noted that the distance between the center of circular pivot region 64 and the center of circular pivot region 86, or the center of pin 66 and the center of pin 88, or the third axis 72 and the sixth axis 92, is equal to R₁. It should further be noted that the distance between the center of circular pivot region 84 and the center of circular pivot region 86, or the center of pin 80 and the center of pin 88, or the fifth axis 90 and the sixth axis 92, is equal to R₂.

The pins 66, 74, 80, and 88 are all held in place with captivating screws 94, and the pins 62, 66, 74, 80, and 88 are all held within the circular pivot regions 60, 64, 56, 84, and 86, respectively, with washers 98 and C-rings 96.

Referring to FIG. 3, the elements of the angular adjustment mechanism 11 are shown in greater detail. Referring to FIG. 4, the elements of the angular adjustment mechanism 11 are again shown in greater detail. A first spacer 100 is used between the first lever 54 and the third lever 68. A second spacer 102 is used between the second lever 58 and the third lever 68. A third spacer 104 is used between the third lever 68 and the fifth lever 82.

Referring to FIG. 5, the angular adjustment mechanism 11 is shown in its two extreme angular positions. In the ideal case, the angular position of the binocular assembly, or the eyepiece 12, is defined as Θ₁, and the ideal angular position of the mirror 24 is defined as Θ₂, wherein,

    Θ.sub.2 =Θ.sub.1 /2

However, the actual angular position of the mirror 24, defined as β, deviates from the ideal angular position, Θ₂, because of an angular error caused, in combination, by the first lever 54, or the second lever 58, pivoting about axis the first axis 28, or the second axis 70, respectively, at a radius of R₁, the fourth lever 78 pivoting about the first axis 28 at a radius of R₂, and the differential motion of the fifth lever 82, otherwise known as the pendulum lever. Nevertheless, over the range of motion of the binocular assembly, or the eyepiece 12, which is typically ±22.5°, this deviation is reasonably small.

The actual angular position of the mirror 24 can be expressed by the following equation, ##EQU1## The angular position of the fifth lever 82, or the pendulum lever, is defined as α, and it can be expressed by the following equation, ##EQU2## The deviation of the angular position of the mirror 24 can be expressed by the following equation, ##EQU3## Thus, when the binocular assembly, or the eyepiece 12, is in its two extreme position angular positions, which is typically Θ₁ =±22.5°, the deviation of the angular position of the mirror 24 would only be +4/-4.5 mrad resulting in an optical image shift of only ±0.5 min. This calculation takes a diametric axial tolerance of 0.05 mm into consideration. At this point it should be noted that all of the levers 54, 58, 68, 78, and 82, may be fabricated from many different types of material, but rigid metals such as aluminum, brass or steel are preferred.

With the preferred embodiment of the present invention angular adjustment mechanism 11 now fully described it can thus be seen that the primary objective set forth above is efficiently attained and, since certain changes may be made in the above described mechanism 11 without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense. 

What is claimed is:
 1. A mechanism for precisely adjusting an eyepiece of an optical assembly by allowing said optical assembly and a mirror assembly, disposed within said optical assembly, to rotate about a common axis, said mechanism comprising:an optical assembly having an eyepiece for viewing an optical image therethrough, a first pivotal engagement means and a second pivotal engagement separated by a first operative length, said first pivotal engagement means having a center defining a first axis, said second pivotal engagement means having a center defining a second axis; a mirror assembly disposed within said optical assembly for reflecting said viewed image; a first lever fixedly integrated into said optical assembly have a third pivotal engagement means and a fourth pivotal engagement means separated by a second operative length, said third pivotal engagement means operatively engaged with said first pivotal engagement means for rotating said optical assembly about said first axis, said fourth pivotal engagement means having a center defining a third axis; a second lever having a fifth pivotal engagement means and sixth pivotal engagement means separated by said second operative length, said fifth pivotal engagement means operatively engaged with said second pivotal engagement means for providing rotation about said second axis, said sixth pivotal engagement means having a center defining a fourth axis; . a third lever having a seventh pivotal engagement means, an eighth pivotal engagement means separated from said seventh pivotal engagement means by said first operative length, and a ninth pivotal engagement means separated from said eighth pivotal engagement means by said second operative length, said seventh pivotal engagement means, said eighth pivotal engagement means, and said ninth pivotal engagement means positioned so as to form a right triangle with said eighth pivotal engagement means at a right angle vertex, said seventh pivotal engagement means operatively engaged with said fourth pivotal engagement means for providing rotation about said third axis, said eighth pivotal engagement means operatively engaged with said sixth pivotal engagement means for providing rotation about said fourth axis, said ninth pivotal engagement means having a center defining a fifth axis; a fourth level fixedly integrated into said mirror assembly having a tenth pivotal engagement means and an eleventh pivotal engagement means separated by a third operative length, said tenth pivotal engagement means operatively engaged with said first pivotal engagement means for rotating said mirror assembly about said first axis, said eleventh pivotal engagement means having a center defining a sixth axis, said third operative length being twice the length of said second operative length; and a fifth lever having a twelfth pivotal engagement means and a thirteenth pivotal engagement means separated by said first operative length, said twelfth pivotal engagement means operatively engaged with said ninth pivotal engagement means for providing rotation about said fifth axis, said thirteenth pivotal engagement means operatively engaged with said eleventh pivotal engagement means for providing rotation about said sixth axis, such that a rotation of said optical assembly about said first axis at a first angular speed results in a rotation of said mirror assembly about said first axis at a second angular speed without causing significant optical image shifts at said eyepiece, wherein said first angular speed is twice said second angular speed.
 2. The mechanism as defined in claim 1, wherein said first pivotal engagement means is a cylindrical shaft, and said second pivotal engagement means is a cylindrical pin.
 3. The mechanism as defined in claim 2, wherein said optical assembly is a binocular assembly of an ophthalmoscope.
 4. The mechanism as defined in claim 1, wherein said mirror assembly is comprised of:a mirror; and a mirror mount for securing said mirror thereto.
 5. The mechanism as defined in claim 1, wherein said first lever is integrated into a prism frame which is fixedly secured to said optical assembly.
 6. The mechanism defined in claim 5, wherein said third pivotal engagement means is a circular aperture formed in said prism frame, and said fourth pivotal engagement means is a circular pivot.
 7. The mechanism as defined in claim 1, wherein said fifth pivotal engagement means is a circular pivot, and said sixth pivotal engagement means is a circular pivot.
 8. The mechanism as defined in claim 1, wherein said seventh pivotal engagement means, said eighth pivotal engagement means, and said ninth pivotal engagement means are all cylindrical pins.
 9. The mechanism as defined in claim 8, wherein all of said cylindrical pins are held in place with captivating screws.
 10. The mechanism as defined in claim 1, wherein said tenth pivotal engagement means is a means for attaching said mirror assembly to said first engagement means, and said eleventh pivotal engagement means is a cylindrical pin.
 11. The mechanism as defined in claim 10, wherein said cylindrical pin is held in place with a captivating screw.
 12. The mechanism as defined in claim 1, wherein said twelfth pivotal engagement means is a circular pivot, and said thirteenth pivotal engagement means is a circular pivot. 